2009-05-19_REVISION - M1977416 (28)

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COR-030000 Stormwater Management Plan iv) Earth/rock berms l?arth/rock berms serve as erosion and sediment control, and slow down the flow rate of the runoff. At down gradient locations, berms are installed where overland sheet flow has the potential to leave the site. In up-gradient areas perimeter control may be added to limit on-site flows or protect off-site features. Such controls should be suitable to the application. Berms will remain in place until areas up-gradient of controls are stabilized. Berms are typically used to slow runoff from the mine working areas, and at the bottom of the WRA. v) Silt fence Silt fence is rarely used at Sunday Mines, and will only be used if conditions warrant. Silt fence consists of geotextile fabric installed with at least six inches of the fabric trenched into the soil; wooden stakes are attached on the down-gradient side. Wire- backed fence may be used or additional stakes or lathe may be added on the up- gradient side for strengthening the fence around comers or in high wind conditions. Silt fence provides sediment control by reducing water velocity and ponding water to facilitate the deposition of sediment on the up-gradient side of the fence. Silt fence applications include, but are not limited to: project perimeter control, secondary containment, and containment for any disturbed or staging area. Silt fence will be inspected regularly for sediment accumulation, tear or holes in the fabric, broken stakes, and gaps in the fabric, or areas where the fabric needs to be re-attached to the wooden stakes. Maintenance includes repairing the items noted, removing sediment accumulation one-third the height of the fence, or replacing the fence as needed. vi) Stabilized material staging are A stabilized staging area is a specific location on or near the project site for stockpiling/staging materials and equipment for use on-site. A stabilized staging area allows for a central location for deliveries and storage of equipment when not in use, and reduces disturbance of areas of the site not scheduled for disturbance through mining activities. Stabilized staging areas generally consist of a cleared area of the site with perimeter control (e.g. silt fence, berms and/or construction fencing). Stabilized staging areas shall be implemented as needed on site. They should be positioned to reduce the need for relocation and be placed out of areas of active mining activity. Stabilized staging areas will be inspected for adequate perimeter control. Stabilized staging areas should be repaired or modified as needed. vii) Temporary Sediment Basins Temporary sediment basins are small impoundments that can be used to capture stormwater runoff and allow sediment to settle out before it leaves the site. They are usually installed in a drainageway or other point of discharge from a disturbed area. Temporary diversions can be used to direct runoff to the sediment basin. Sediment basins detain sediments in stormwater runoff to protect receiving streams, lakes, Denison Mines (USA) Corp. Sunday Mines SWMP 11